1. Field of the Invention
The present invention relates to a semiconductor integrated circuit wafer, a semiconductor integrated circuit chip, and a method of testing a semiconductor integrated circuit wafer which are suitable for detecting defects of the semiconductor integrated circuit by using a build in self test (BIST) circuit.
Priority is claimed on Japanese Patent Application No. 2008-099664, filed Apr. 7, 2008, the content of which is incorporated herein by reference.
2. Description of Related Art
In a test of a semiconductor integrated circuit wafer, probe pins (exploring needles) contact with input-output pads (external electrodes) in the semiconductor integrated circuit such as a memory, and input test pattern signals which are supplied from a tester via the probe pins, and thus electrical characteristics can be measured to determine whether or not the semiconductor integrated circuit wafer is defective. When the probe pins contact with the input-output pads, there may be scars caused by contacting the input-output pad to the probe pins. If the scars occur in the input-output pads, when wires are bonded to the input-output pads or bumps are constructed, the scars lead to an increase in defects and to a decrease in reliability of connection. For this reason, it is necessary to improve the structure of the input-output pad or the adjustment of contact pressure of the probe pins in order to make it possible to safely test by reducing the scars.
On the other hand, there is a method of using a built in self test (BIST) circuit as a technique of efficiently testing the semiconductor integrated circuit. However, when the BIST circuit is built in a circuit region of the semiconductor integrated circuit, the chip size of the entire semiconductor integrated circuit is increased, and thus the chip cost rises. In addition, unnecessary BIST circuit portions remain after production is complete. Thereby the consumption power increases.
In order to solve the problems of increase in the chip size or increase in the consumption power, there is proposed a structure in which the BIST circuit and the pads for testing are provided in a scribe region (for example, refer to Japanese Unexamined Patent Application, First Publication, No. 2002-176140). In this related art, there is a need for the probe pins coming into contact with both the pads for testing the BIST circuit in the scribe region and the input-output pads of a semiconductor integrated circuit region in order to be electrically connected with each other via the probe pins as a transmission path. For this reason, there are problems in that (i) the number of the probe pins is increased, so that a testing tool (probe card) is complicated and the cost is increased; and (ii) the electrical characteristics of the testing tool affects the test of the semiconductor integrated circuit.
In addition, there is proposed another structure in that the BIST circuit and the pads for testing are provided in the scribe region, which are electrically connected with the input-output pads in the semiconductor integrated circuit region by wiring (for example, refer to Japanese Unexamined Patent Application, First Publication, No. 2003-124275). In this related art, when the semiconductor chips are individually separated, the scribe region and the wiring for connection are also separated at the same time. However, due to a finished state of the cut surface, there may be an electrical defect such as a short circuit or the like between the wiring for connection.
In addition, there is disclosed a technique of forming wiring for connecting a testing circuit and a functional circuit, and switch elements for electrically separating the wiring (for example, refer to Japanese Unexamined Patent Application, First Publication, No. 2001-085479). In this related art, there is no description about the pads of the testing circuit (BIST circuit) and the functional circuit (semiconductor integrated circuit) and effects thereof, and there is no suggestion of a method which improves the scars of the input-output pads that should be solved.